The proliferation of portable battery powered devices, such as cellular telephones, video cameras, portable laptop computers, and the like, has increased dramatically in the last several years and this trend is expected to continue. These devices typically use a rechargeable battery that is built into the device to provide the needed power. The length of time that the battery powers the device is dependent primarily upon the size of the battery and the number of energy consuming features built into the device. For instance, in response to consumer demand, cell phone manufacturers often incorporate into the phones features such as the ability to send and receive digital pictures and/or text messages, and even real-time video transmissions. Unfortunately, the inclusion of these features usually places additional demands on the rechargeable batteries that power the cell phones. The net result is that cell phone run times are becoming shorter due to the increased power demands. At the same time that the electrical demand placed on the battery is increasing, the size and weight of cell phones is decreasing. As the size of the cell phone is reduced, the size of the battery compartment built into the cell phone is also generally reduced. The combination of these two trends, i.e. increased electrical demand and reduced battery size, often causes cell phone users to experience a lost telephone call or data transmission due to the depletion of the phone battery at an inopportune moment. An additional trend that complicates resolution of this problem is that most cell phones require a battery that has specific size and shape characteristics. In order to encourage consumers to purchase replacement batteries from the cell phone manufacturer, the cell phones are made with batteries that have unique shapes, locking mechanisms, voltage requirements, etc. Furthermore, the recharging port built into the cell phones limit the type of charger that can be connected to the cell phone. Collectively, these factors limit the consumer's ability to readily replace the depleted battery with another power source.
Numerous attempts have been made to develop a versatile auxiliary portable power supply for cellular telephones. For example, U.S. Pat. No. 6,127,801 to D. Manor, for “Battery Pack Assembly”, discloses a power supply that includes a battery pack and a base unit which has bidirectional circuitry. In U.S. Pat. No. 6,479,963 to D. Manor and G. Weinstein, for “Rechargeable Battery Packs”, there is described a rechargeable battery pack for use with cellular telephones or other portable devices, including a conventional rechargeable battery for powering the device, and a user-replaceable primary cell for recharging the rechargeable cell when desired by the user, thus acting as a built-in charger for the device. This battery pack uses as its additional energy source a replaceable primary cell or battery, which when depleted, needs to be replaced by a fresh battery. In another example, U.S. Pat. No. 6,709,784 to O. Resch, for “Back-up Battery for a Cellular Telephone” there is disclosed a battery pack that can be plugged into a cellular phone's contact to recharge the phone's built-in rechargeable battery and/or to directly power the cell phone. This invention does not provide any voltage converting circuitry to match the battery pack output voltage to that required for charging the phone's rechargeable battery, and relies on the internal charge control circuits of the phone to ensure correct voltage compatibility. Furthermore, the battery is preferably packaged with the plug that allows the battery pack to be connected to the phone. Consequently, when the battery is depleted, the entire battery pack, including the plug, must be discarded, increasing consumer costs.
Therefore, there exists a need for an auxiliary direct current power source that uses a commonly available battery that the consumer can readily insert into and remove from a reusable housing, and that can be either a readily available primary cell or battery, or a secondary cell or battery with the added option of recharging the secondary cell or battery inside the device's housing, using the device's usual charging method. The power supply needs to be lightweight, volume-efficient and easily adaptable to a wide array of cell phones that utilize batteries of various shapes and sizes.
Additionally, rechargeable batteries built into portable electronic devices are generally expensive and not widely available. Replacement of such originally equipped batteries with lower cost or more readily available types of batteries generally results in degradation of the available power for the device, or of the use-time of the device, since the built-in batteries supplied by the device manufacturer have usually been selected for optimum performance and operating time. This is particularly true of lap-top and other portable computers, where the critical nature of the tasks performed generally negates compromise in built-in battery selection and use. Therefore, there have been few previous attempts at providing cheaper or more versatile battery power solutions for such portable electronic devices.
There therefore also exists a need for providing auxiliary battery packs to provide additional power to augment the internal rechargeable battery of the device, thereby providing additional power from sources less costly and more readily available than the generally expensive rechargeable batteries built into the device, yet without compromising performance of the device.
The disclosures of each of the publications mentioned in this section and in other sections of the specification, are hereby incorporated by reference, each in its entirety.